Abstract

Both natural influenza infection and current seasonal influenza vaccines primarily induce neutralising antibody responses against highly diverse epitopes within the “head” of the viral hemagglutinin (HA) protein. There is increasing interest on redirecting immunity towards the more conserved HA-stem or stalk as a means to broaden protective antibody responses. Here we examined HA-stem-specific B cell and T-follicular helper (Tfh) cell responses in the context of influenza infection and immunisation in mouse and monkey models. We found that during infection the stem domain was immunologically subdominant to the head in terms of serum antibody production and antigen-specific B and Tfh responses. Similarly, we found HA-stem immunogens were poorly immunogenic compared to the full-length HA with abolished sialic acid binding activity, with limiting Tfh elicitation a potential constraint to the induction or boosting of anti-stem immunity by vaccination. Finally, we confirm that currently licensed seasonal influenza vaccines can boost pre-existing memory responses against the HA-stem in humans. An increased understanding of the immune dynamics surrounding the HA-stem is essential to inform the design of next-generation influenza vaccines for broad and durable protection.

Abstract

BACKGROUND. Varicella-zoster virus (VZV) is under consideration as a promising recombinant viral vector to deliver foreign antigens including HIV. However, new vectors have come under increased scrutiny since vaccination with Ad5-vectored HIV vaccine trials demonstrated increased HIV risk in individuals with pre-immunity to the vector which was thought to be associated with mucosal immune activation (IA). Therefore, defining the impact of VZV vaccination on IA is particularly important with the prospect of developing an HIV/VZV chimeric vaccine. METHODS. VZV-seropositive healthy Kenyan women (n=44) were immunized with high dose live-attenuated VZV vaccine, and the expression of IA markers including CD38 and HLA-DR on CD4 T cells isolated from blood, cervix and rectum, markers of cell migration and tissue retention and the concentration of genital and intestinal cytokines were assessed. A delayed group (n=22) was used to control for natural variations in these parameters. RESULTS. Although immunogenic, VZV vaccination did not result in significant difference in the frequency of cervical activated (HLA-DR+CD38+) CD4 T cells (median 1.61%, IQR 0.93%-2.76%) at 12 weeks post-vaccination when compared to baseline (median 1.58%, IQR 0.75%-3.04%), the primary outcome for this study. VZV vaccination also had no measurable effect on any of the IA parameters at 4, 8 and 12 weeks post-vaccination. CONCLUSION. This study provides the first-ever evidence about the effects of VZV-vaccination on human mucosal IA status and supports further evaluation of VZV as a potential vector in an HIV vaccine. TRIAL REGISTRATION. ClinicalTrials.gov NCT02514018. FUNDING. Primary support from CIHR. For others see below.

Abstract

Vaccines are among the most effective public health tools for combating certain infectious diseases such as influenza. The role of the humoral immune system in vaccine-induced protection is widely appreciated; however, our understanding of how antibody specificities relate to B cell function remains limited due to the complexity of polyclonal antibody responses. To address this, we developed the Spec-seq framework, which allows for simultaneous monoclonal antibody (mAb) characterization and transcriptional profiling from the same single cell. Here, we present the first application of the Spec-seq framework, which we applied to human plasmablasts after influenza vaccination in order to characterize transcriptional differences governed by B cell receptor (BCR) isotype and vaccine reactivity. Our analysis did not find evidence of long-term transcriptional specialization between plasmablasts of different isotypes. However, we did find enhanced transcriptional similarity between clonally related B cells, as well as distinct transcriptional signatures ascribed by BCR vaccine recognition. These data suggest IgG and IgA vaccine–positive plasmablasts are largely similar, whereas IgA vaccine–negative cells appear to be transcriptionally distinct from conventional, terminally differentiated, antigen-induced peripheral blood plasmablasts.

Abstract

Despite showing success in treating melanoma and haematological malignancies, adoptive cell therapy (ACT) has generated only limited effects in solid tumors. This is, in part, due to a lack of specific antigen targets, poor trafficking/infiltration and immunosuppression in the tumor microenvironment. In this study, we combined ACT with oncolytic virus vaccines (OVV) to drive expansion and tumor infiltration of transferred antigen-specific T cells, and demonstrated that the combination is highly potent for the eradication of established solid tumors. Consistent with other successful immunotherapies, this approach elicited severe autoimmune consequence when the antigen targeted was a self-protein. However, modulation of IFNα/β signaling, either by functional blockade or rational choice of an OVV backbone, ameliorated autoimmune side effects without compromising antitumor efficacy. Our study uncovers a pathogenic role for IFNα/β in facilitating autoimmune toxicity during cancer immunotherapy and offers a safe and powerful combinatorial regimen with immediate translational applications.

Abstract

The adjuvanted varicella-zoster virus glycoprotein E (VZV gE) subunit herpes zoster vaccine (HZ/su) confers higher protection against HZ than the live attenuated zoster vaccine (ZV). To understand the immunologic basis for the different efficacies of the vaccines, we compared immune responses to the vaccines in adults 50- to 85-year-old. gE-specific T cells were very low/undetectable before vaccination when analyzed by FluoroSpot and flow cytometry. Both ZV and HZ/su increased gE-specific responses, but at peak memory response (PMR) after vaccination (30 days after ZV or after the second dose of HZ/su) gE-specific CD4+ and CD8+ T-cell responses were ≥ 10-fold higher in HZ/su compared with ZV recipients. Comparing the vaccines, T cell memory responses, including gE- and VZV-IL2+ spot-forming cells (SFC), were higher in HZ/su recipients and cytotoxic and effector responses were lower. At 1 year after vaccination, all gE-Th1 and VZV-IL2+ SFC remained higher in HZ/su compared to ZV recipients. Mediation analyses showed that IL2+ PMR were necessary for the persistence of Th1 responses to either vaccine and VZV-IL2+ PMR explained 73% of the total effect of HZ/su on persistence. This emphasizes the biological importance of the memory responses, which were clearly superior in HZ/su compared with ZV participants.

Abstract

In the mid-1990s, whole-cell (wP) pertussis vaccines were associated with local and systemic adverse events, which prompted their replacement with acellular (aP) vaccines in many high-income countries. In the past decade rates of pertussis disease have increased in children receiving only acellular pertussis vaccines. We compared the immune responses to acellular pertussis boosters in children who received their initial doses with either wP or aP vaccines using activation-induced marker (AIM) assays. Specifically, we examined pertussis-specific memory CD4+ T cell responses ex vivo, highlighting a Type 2/Th2 versus Type 1/Th1 and Th17 differential polarization as a function of childhood vaccination. Remarkably, after a contemporary aP booster, cells from donors originally primed with aP were 1) associated with increased IL-4, IL-5, IL-13, IL-9 and TGF-β and decreased IFNγ and IL-17 production; 2) defective in their ex vivo capacity to expand memory cells; and 3) less capable to proliferate in vitro. These differences appeared to be T cell-specific, since equivalent increases of antibody titers and plasmablasts after aP boost were seen in both groups. In conclusion, our data suggest that long lasting effects and differential polarization and proliferation exists between adults originally vaccinated with aP versus wP despite repeated acellular boosters.

Abstract

Vaccine responses vary by geographic location. We have previously described how HIV-associated inflammation leads to fibrosis of secondary lymph nodes (LNs) and T cell depletion. We hypothesized that other infections may cause LN inflammation and fibrosis, in a process similar to that seen in HIV infection, which may lead to T cell depletion and affect vaccine responses. We studied LNs of individuals from Kampala, Uganda, before and after yellow fever vaccination (YFV) and found fibrosis in LNs that was similar to that seen in HIV infection. We found blunted antibody responses to YFV that correlated to the amount of LN fibrosis and loss of T cells, including T follicular helper cells. These data suggest that LN fibrosis is not limited to HIV infection and may be associated with impaired immunologic responses to vaccines. This may have an impact on vaccine development, especially for infectious diseases prevalent in the developing world.

Abstract

Enterotoxigenic Escherichia coli (ETEC) infections are highly prevalent in developing countries where clinical presentations range from asymptomatic colonization to severe cholera-like illness. The molecular basis for these varied presentations, that may involve strain-specific virulence features as well as host factors, have not been elucidated. We demonstrate that when challenged with ETEC strain H10407, originally isolated from a case of cholera-like illness, blood group A human volunteers developed severe diarrhea more frequently than individuals from other blood groups. Interestingly, a diverse population of ETEC strains, including H10407, secrete a novel adhesin molecule, EtpA. As many bacterial adhesins also agglutinate red blood cells, we combined the use of glycan arrays, biolayer inferometry, and non-canonical amino acid labeling with hemagglutination studies to demonstrate that EtpA is a dominant ETEC blood group A specific lectin/hemagglutinin. Importantly, we also show that EtpA interacts specifically with glycans expressed on intestinal epithelial cells from blood group A individuals, and that EtpA-mediated bacterial-host interactions accelerate bacterial adhesion and the effective delivery both heat-labile and heat-stable toxins of ETEC. Collectively, these data provide additional insight into the complex molecular basis of severe ETEC diarrheal illness that may inform rational design of vaccines to protect those at highest risk.